In vitro evaluation of slow-release urea compounds

Area of Science:

• Animal Science
• Ruminant Nutrition
• Agricultural Chemistry

Background:

• Nonprotein nitrogen sources are crucial for ruminant diets.
• Slow-release urea (SRU) compounds offer potential for controlled nitrogen release.
• Understanding SRU effects on ruminal fermentation and nutrient utilization is vital for optimizing animal nutrition.

Purpose of the Study:

• To evaluate the impact of different slow-release urea (SRU) compounds on ruminal fermentation, nutrient degradation, and nitrogen utilization.
• To assess the ammonia-N release rate of various SRU compounds in a batch culture system.
• To compare the effects of SRU compounds against conventional urea in a continuous culture system.

Main Methods:

• Experiment 1: Dual-flow continuous culture system with 4 treatments (control urea, 3 SRU compounds) in a 4x4 Latin square design.
• Experiment 2: Batch culture system to determine ammonia-N release rates of SRU compounds.
• Analysis included ruminal pH, volatile fatty acids (VFA), ammonia-N kinetics, nutrient degradability, and nitrogen metabolism.

Main Results:

• SRU compounds, particularly SRU1, influenced volatile fatty acid profiles, with SRU1 showing a lower acetate:propionate ratio and less protein degradation compared to control.
• No significant effects of SRU treatments were observed on ruminal pH, ammonia-N kinetics, nutrient degradability, or overall nitrogen flow.
• Experiment 2 revealed significant differences in nitrogen release rates among SRU compounds, with SRU1 releasing nitrogen faster than SRU2 and SRU3.

Conclusions:

• Different SRU compounds exhibit distinct nitrogen release patterns, influencing ruminal fermentation.
• While SRU1 demonstrated potential for favorable fermentation characteristics, overall nutrient degradability and nitrogen utilization were not improved.
• The varying nitrogen release rates of SRU compounds necessitate careful consideration for their application in different ruminant diets.